July 29, 2005
The Ministry of the Environment has compiled the annual report of FY 2004 ozone layer monitoring covering status of (i) ozone depletion, (ii) atmospheric concentrations of ozone depleting substances (ODS), and (iii) solar ultraviolet radiation, pursuant to the Law concerning the Protection of the Ozone Layer through the Control of Specified Substances and Other Measures (the "Ozone Layer Protection Law").
|1.||State of the ozone layer|
Global total ozone amount has been continuously at a lower level compared to that had been seen before the 1980's (an average amount between 1964 and 1980). Especially, a marked decline is noted in high latitudes in spring. In Japan, a long-term decline is observed in the skies above Sapporo (Hokkaido), Tsukuba (Kanto area) and Kagoshima (Kyushu area). The decline is most prominent in the sky above Sapporo.
In 2004, the area of the ozone hole and the amount of ozone depleted over the Antarctica was the third smallest in past ten years. This is due to a sudden increase of the temperature in stratosphere, and it cannot be confirmed that the ozone hole is recovering. The ozone layer over the Antarctica remains still in critical condition.
|2.||State of atmospheric concentrations of ozone depleting substances (ODS)|
The concentration of CFC-12 has been remaining broadly unchanged since the latter half of the 1990s, and the concentrations of CFC-11 and -113 have been in decline. On the other hand, the concentrations of hydrochlorofluorocarbons (HCFC) and hydrofluorocarbons (HFC) have been increasing.
|3.||State of solar ultraviolet radiation|
Monthly means of harmful ultraviolet rays (UV-B) observed at Sapporo, Tsukuba, Kagoshima and Naha (Okinawa) remained flat or slightly increased throughout the year compared with the reference value (monthly mean between 1991 (1990 in case of Tsukuba) and 2003) except for that marked in Naha in January 2004. In Tsukuba and Kagoshima, the value exceeded far from the reference probably reflecting the increase of hours of sunlight.